Rocker mechanisms for office chairs are known from the prior art. These are assemblies of relatively simple construction in the seat substructure of chairs in which a backrest support is rigidly connected to a seat support of the chair. The seat support-backrest support combination thus formed can, by means of the rocker mechanism, which connects the seat support-backrest support combination to the chair vertical column, be pivoted rearward about a pivot axis running perpendicular to the chair longitudinal direction when the user of the chair leans on the backrest. Only very simple movements can be realized by means of rocker mechanisms of said type. Thus, when the occupant leans rearwardly, both the back and seat tilt, maintaining the same angle therebetween.
Further, synchronous rocker mechanisms are known from the prior art. These are to be understood to mean assemblies in the seat substructure of chairs, which assemblies serve to realize a coupled-together kinematic mechanism which provides a certain movement of the seat part and backrest relative to one another. By means of these synchronous mechanisms, while both the seat part and the backrest are moved, the movement may be in a different controlled path. On the seat support there is mounted the seat, which is generally provided with a cushioned seat surface. The backrest support, which customarily extends rearward and upwardly relative to the seat support, bears the backrest of the chair.
To realize the desired synchronous movement of seat support and backrest support, it is customarily the case in such synchronous mechanisms that the seat support and backrest support are articulately coupled, either directly to one another or with the aid of additional coupling elements. Such synchronous mechanisms are used in particular in office chairs. They are generally of complex construction, expensive to produce and cumbersome to assemble.